This isn't what I've seen at CoffeeSnobs in the mid-priced machines forum.

The evidence of maladjusted OPVs is mixed, at best. Some users have reported gauge readings of 11.5 bar that came down to 9 bar when they reduced their dose a little, These users report excellent taste. I think this represents the current norm.

Breville is making adjustment available, with at least one service center in each major city set up and ready to go. Some service centers are better than others, as you would expect. Apparently they've been advised to set the OPV to less than 10 bar with the blind, and some users report that the service center set it to exactly 9 bar, which results in under-extraction. These users have to go back and get it set to 9.5 bar with the blind to get 9.0 in real life.

The CG owner's thread for the BES900XL is certainly interesting, especially the advice on how to adjust the OPV: click here. It appears that the first batch of BES900XLs in the USA have maladjusted OPVs, and probably for a very funny reason.

They calibrated the OPV with a Scace II installed in the machine, and the Scace itself limits the pressure to something close to 9.5 bar. When you replace the Scace with a blind, you find out that the OPV is actually set to 13+ bar. So they have a so-called calibration step in manufacturing that's a complete waste of time.

Fortunately, the OPV is adjustable, but the fiasco makes you wonder if the Breville people know what they're doing at all.

Is there a taste difference between a machine that's putting 9 bar through the puck with the right combination of time and volume due to the grind, dose, and tamp, and one that puts 9 bar through any old combination of GDT because the OPV won't have it any other way? Maybe not, but I'm no expert on these things.

Fortunately, the OPV is adjustable, but the fiasco makes you wonder if the Breville people know what they're doing at all.

This kind of thing is a possibility, (probability) with manufacturing businesses that have many layers between the guys who design and build, and the guys who sell, market, what-have-you. The same thing happens in the car business, especially on the domestic side, where the "shots" are called by bean counters. The engineers obviously know plenty, but are often overruled. Europeans like BMW tend to have more engineers at the top decision-making levels, and it shows in their products. Back to your quote... ultimately you're right... at a big appliance manufacturer like Breville, probably 95% of the employees really do not know what they are talking about, but that is by design, and comes with the territory. Not unusual. And no reason not to buy a great product from them, either. IMHO.

I'm specifically referring to the calibration step. It appears that the engineering folks have been misled about what you can do with a Scace II, and also about what the factory is actually doing. It appears that the OPVs aren't being calibrated in manufacturing at all, and even if they were they wouldn't be right because they're trying to calibrate a self-regulated stream of water. The Scace II doesn't block the flow, so it can't really be used to calibrate an OPV. It's fine for measuring temperature, but that's all it's good for.

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